Friss, free space path loss calculator.

Calculates the Free Space Transmission Loss (FSTL) between two antennas based on:

• Transmit power.
• Transmit and receive antenna gains (Gtx & Grx).
  
• The distance between the two antennas.
• The operating frequency.
  

Given the parameters above, this tool provides the power at the receive and as Prx.